In recent years, an image erasing apparatus is well known which is configured to decolor an image formed on a sheet using coloring materials to be decolored by heating at a predetermined temperature. The image erasing apparatus takes in a sheet on which an image is formed using the coloring materials and heats it while pressurizing the sheet, thereby decoloring the image. The image erasing apparatus performs erase processing of the image by decoloring the image. The image erasing apparatus is used for facilitating re-use of the sheet. Further, there is a known technique that compares the number of times of erase processing counted by the image erasing apparatus with the limited number of re-uses of the sheets or determines re-availability of the sheet based on detection results of the degree of deterioration of the sheet.
According to the image erasing apparatus of the related art, even when important documents or confidential documents are mixed in the sheets which are a target of the erase processing, the erase processing is uniformly performed on the sheet to be erased upon receipt of a request for erasing input by a user. Further, in preparation for a case where the image formed on the sheet is erroneously erased, the image erasing apparatus scans the sheet to be erased, and can preserve the scanning results in a storage device as an image data file before the erase processing. For example, when the confidential documents or the like are mixed in the sheets to be erased, the image erasing apparatus also preserves contents of the confidential documents or the like. Accordingly, a third party can acquire confidential information by analyzing hardware of the image erasing apparatus. In other words, the image erasing apparatus has problems in terms of information security management.